Pityriasis rosea is a common, self-limited rash in teens and young adults, likely linked to reactivation of human herpesviruses 6 and 7. It starts with one larger patch and then spreads to the trunk, usually clearing on its own in 6 to 8 weeks.
Key symptoms
- One oval pink patch first (herald patch)
- Days to 2 weeks later, many smaller patches on the trunk
- Mild itch or none
- Sometimes a mild cold-like illness before the rash
What you find on exam
- Salmon-pink oval patches with a fine ring of scale just inside the edge
- Long axis along skin lines, forming a Christmas tree pattern on the back
- Face, palms and soles usually spared
- Check palms, soles and mouth to rule out secondary syphilis
Tests
- Diagnosis is clinical
- RPR or another syphilis test if sexually active or palms and soles are involved
- KOH prep of scale to rule out tinea
- Pregnancy test in women who could be pregnant, since it can affect pregnancy
Treatment basics
- Reassurance: the rash fades in 6 to 8 weeks
- Oral antihistamines and moisturizers for itch
- Mild topical steroids for itchy patches
- Acyclovir in selected cases, such as early widespread disease or pregnancy
Red flags
- Rash on palms and soles (think of secondary syphilis)
- Pregnancy, mostly in the first 15 weeks (higher risk of miscarriage)
- Rash lasting more than 3 months, or with fever and feeling very ill
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.